This project encompasses morphological analyses of developing neurons grown under in situ and in vitro conditions. Morphological studies of aggregates prepared from dissociated embryonic cells from various parts of the chick brain are intended to elucidate the nature of the processes of self-assembly in these unique structures, with the expectations of gaining a better understanding of the basic mechanisms involved in neurogenesis and synaptogenesis in developing systems in situ. Investigations in the cerebellar cortex in situ are primarily aimed at this time at elucidating the mechanisms of redistribution of synapses on neurons in late stages of neurogenesis, a phenomenon evidenced by the existence of "temporary spines and synapses"